Electric immersion heater



Nov. 28, 1950 H. L. BARN EBEY ELECTRIC IMMERSION HEATER 4 Sheets-Sheet 1 Filed Dec. 23, 1948 INVENTOR Herbert [J Barneb 154 "1 Mxm H. L. BARNEBEY ELECTRIC IMMERSION HEATER Nov. 28, 1950 4 Sheets-Sheet 2 Filed Dec. 25, 1948 Herbert L. Barnebe /Q I M Z 9AM Nov. 28, 1950 BARNEBEY 2,531,385

ELECTRIC IMMERSION HEATER Filed Dec. 25, 1948 4 Sheets-Sheet 3 Fig.5. /22

i I\ 28 g i 29 29 a; 21 28 INVENTOR Herbert L,.Barnebe1 AT ORNEY5 Nov. 28, 1950 4 Sheets-Sheet 4 Filed Dec.

R. w an @NQ Rm M w& .v R m aw N 2 M NM 0 m a e H% mm a o a o e 0 E H 5 SEM E 95% I r I II J a 0 a U mw iw M m it H w H. 0 It 11 D nm @M QM mw Q a QM mm m ...v r I II I H mm. Q mm a h QM mm Patented Nov. 28, 1950 UNITED STA ES PATENT OFFICE I 2,531,385 anaemic MMERsIoN HEATER Herbert L. Barnebey, Richmond Township, Allegheny County, Pa, assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application December 23, 1948, Serial No. 66,892

16 Claims. (o1. 219-38) the jacket without decomposing that substance or,

interfering with its circulation through the heater and without danger of short-circuiting.

In the heating of reaction vessels, such as those used'in' the varnish and resin industry. by means of vapor jackets, electric immersion heaters are.

used which extend into the jacket below the normal level of the pool of vaporizing liquid therein.

-- While formerly such immersion heaters included a heating element encased in a layer of insulating material, a heating lag and a severe limitation on the heating capacity were introduced which adversely affected the efiiciency of the operation Subsequently, it became common to use ,bare resistor heaters immersed in the vaporizing liquid or substance, usually one of an organic nature;

such as Dowtherm which. does not readily decompose under extreme heating demands. The bare resistors used often comprised a conventional type of nickel-chrome electric resistance conductor alloy such as Nichrome.

When it is considered that commercial installations employing such vapor heating jackets with electric immersion heaters may require a power input in excess of 300 kilowatts, it is at once-realized what a problem it is to provide a" structure which will quickly and'safely enable heat inputs of such magnitude to be made and sustained. The solution of this problem involves the available voltage andpower, the permissible size and height of the reaction vessels and jacket, the material to be treated and the other economic, physical and structural consid erations present. 'In one case, the necessary heating input is obtained by a novel design'oi arcuate immersion heaters in a horizontal oblique-e arrangement with looped ribbon resistors on edge in banks therein. Such a construction is generaly shown and claimed in United States patent No. 2,434,016 issued January 6, 1948,:the

application for which was copending with the? applicants pending United 1 States application Serial No. 656,570 flledMarch 23, 19.46. The instant applicationis a continuationrin-part oithe latter application S. N.

70 which was late" abandoned. g v

By theprovision of the insulating lattices in combination with resistors of this invention, the applicant has produced in an electric immersion I eater a compact structure which enables the respective banks of resistors, whether in ribbon ,form or otherwise and whether on edge or otherwise, to be quickly and easily looped back and 1 forth in each bank and assembled both when the heater is new and whenever any replacement or repair may be in order. At the same time, this invention provides a multitude of vertical passages for the easy circulation of vapors and vaporiziug substance past the resistance heating ele- 111821 38 while maintaining appropriate distances bet 'e-en adjacent banks and adjacent portions of loops in'each bank of the elements in a positive manner by means of the lattice-work insulators.

Moreover, the various parts used in constructing the interlocking but somewhat loosely fitted together lattices are made of uniform slensections and of relatively inexpensive maal. Irregular shaped sections have unequal rmal deformation and are subject to internal sses in heating and cooling which cause breakage of parts. The heater of this invention employs rods or rods and plates of generallyuni- 1 form section which do not develop such stresses in service. These sections furthermore are replaceable without complete disassembly of the heater and should breakage occur in handling, a broken part can be removed and a new one inserted without difficulty. Each part is free to contract or elongate due to temperature changes without imposing undue or unsafe stress in companion members. Still further, the parts of the lattices are so constructed that they facilitate the operation of winding the unit with conductor ribbon resistor in banks.

This invention also provides a novel form of corrugated ribbon resistor with lanes in each lattice insulated from adjacent lanes for the loops in each bank, whereby theuser optionally may obtain greater heating capacity per unit length of heater or a shorter length of heater for a given heat input rate. In this way, the provision of curved heaters for requirements of greater magi nitride can on occasion be accommodated by a straight heater. Gther objects and advanta'es of this invention will appear from the following description and the accompanying drawings, which are illustrative only, in which Figure 1 is a central vertical section through the lower portion of a processing vessel-having a vapor heating jacket therearound equipped with immersion heaters constructed in accordance with one embodiment of the invention;

Figure 2 is a partial horizontal section taken along line 11-11 of Figure 1;

Figure 3 is a plan view of one of the immersion heaters in Figure 2 removed from the jacket;

Figure 4 is an elevational view of the closure plate by means of which such a heater is mounted in the jacket;

Figure 5 is a vertical section through the terminal or outer end of such a heater taken along line VV of Figure 3;

Figure 6 is a partial section taken along line VI-VI of Figure l showing the manner of mounting the terminal box at the terminal end;

Figure 7 is a transverse section through the heater taken along line VIIVII of Figure 5;

Figure 8 is a transverse section taken along line VIIIVIII of Figure 3 showing the insulating spacer lattices on an enlarged scale;

Figure 9 is a side elevation of the inner end of the heater;

Figure 10 is an end view of the inner end of the heater with the insulating spacer lattices and resistors omitted;

Figure 11 is a plan view of a heater constituting the preferred embodiment of this invention;

Figure 12 is a side view of the heater shown in Figure 11, with the nearer spaced side bar broken away to show the terminal ends of the corrugated ribbon resistors;

Figure 13 is a view in cross section taken along line XIII-XIII of Figure 12;

Figure 14 is a view in cross section tak n along line XIVXIV of Figure 12;

Figure 15 is an enlarged view of the common electrical bus connection shown in Figure 13 for the ends of the resistors in the respective banks of the heater; and

Figure 16 is a side view of the electrical bus connection shown in Figure 15.

Referring now in detail to the drawings and, for the present, to Figures 1 and 2 particularl for one embodiment of this invention, a processing vessel It has a vapor heating jacket I I surrounding the bottom and lower portion thereof and adapted to contain vaporizable liquid to a level in the neighborhood of the chain line I2. The vessel I0 has a bottom discharge port I3 adapted to be closed by a suitable valve (not shown) The jacket I! has a central passage I4 in alignment with the port I3. The side wall of the jacket II has a plurality of circumferentially spaced ports I5 having their centers substantially in a common horizontal plane intermediate the bottom of the vessel It and the bottom of the jacket. Necks I 8 extend outwardly from the ports I5. These may be simply pieces of pipe of suitable length welded in the ports and having a coupling flange on the outer end. As shown in Figure 2, the necks I6 are disposed at an oblique angle to the radii of the jacket through the centers of the ports. A heater indicated generally at I! is inserted through each neck I6. The heaters may be straight but in the embodiment shown are preferably curved in the horizontal plane to the general form of a spiral and terminate at points spaced from the passage I4. A collecting shell or funnel I8 is supported in the jacket ll between the heater I? and the bottom of the vessel I0 by radial plates I9. The shell has a central opening 20, the edge of which is spaced from the wall of the passage I4. The funnel thus serves to collect condensate dropping from the outer surface of the vessel I0 and deliver it adjacent the inner ends of the heaters H.

The details of construction of the heaters H are shown in Figures 3 through 10. Each heater comprises a horizontal elongated frame including side bars 2I secured to a closure plate or base 22 in the form of a disc adapted to be bolted v to the coupling flange on the neck I5. The bars are secured together at their inner ends by through bolts 23 having spacer sleeves 24 thereon. Insulating spacer lattices 25 are carried by the bars 2I transversely thereto and in spaced relation therealong. As shown in Figure 8, the lattices include vertical separator rods 26 of oval shape in section disposed side-by-side and having transverse registering holes spaced therealong through which round transverse supporting rods 21 extend. The fit of the rods 21 in the holes is relatively loose rather than snug. to permit sufficient independent movement of the rods in case of differential expansion or contraction. The rods 26 and 21 are composed of glass, porcelain, or the like, and are assembled in interlocking relation to constitute the respective lattices. The intermediate rods 21 extend into holes in the bars 2| registering with the corresponding holes through separator rods 26 but terminate short of the outer surfaces thereof. This provides freedom for slight movement of the rods. The top and bottom supporting rods 21 as well as the other supporting rods 21 are retained in position by clamping straps 28. The straps are secured to the bars by bolts 29 and have their ends bent over to enter notches 27 at the ends of the uppermost and lowermost rods 21 with a slight clearance therebetween. While the uppermost supporting rods 21 in each heater I! may not carry the weight of a conductor, as the structure is symmetrical and reversible and may optionally be installed with either side down, it is obviously desirable that all the rods be adapted to act as supports. In any event they function to form with the respective separator rods 25 laterally and vertically extending conductor enclosing cells in each lattice 25. These cells in each lattice are substantially in axial registry with the cells of the lattice or lattices adjacent thereto. These closed cells in the form of rectangles generally, are constructed large enough to accommodate the particular cross section of the resistor that is employed and to allow sufficient clearance for such difierential movement as may occur upon the heating and cooling of the resistance element. Thus, the resistance elements are held in substantially vertical and horizontal alignment in each heater II, separated horizontally by the separator rods 26 and vertically by the supporting rods 21.

A ribbon or strip resistance conductor 30 is wound in lengthwise loops, back and forth longitudinally of the frame and in three vertically spaced banks, the adjacent loops being spaced apart by the vertical separator rods 26 and the several banks by the horizontal supporting rods 21. The conductor is bare and constitutes the resistance heating element of the heater. It is composed of a metal having suitable resistance and durability such as the well known nickelchromium alloy. Each bank of loops is actually formed by a separate piece of conductor strip, the adjacent ends of the several strips being connected in series by vertical lengths of strip 3 I, that connecting the upper two banks being depicted in Figure 3, and that connecting the lower two banks being depicted in Figure 5.

parallel vertical separator strips 56.

f The .construction of the lattices .25 .described above facilitates the winding of the several strips formingrthe-conductor- 30 inbackand forthloops.

For this purpose, the uppermost ,rods 2'! of the lattices are removed and the strip which is to form the intermediate bank of loops is laid in the spaces between the rods 26. The uppermost rods 21 arethen replaced and the :nextlower rods 21 are :removed. The intermediate bankis then pushed downwardly to itsfinal position and the rods .21 thereabove replaced. Thereafter the uppermost bankis Wound in thesame way. The

heater is then turned over and the lowermost bank is similarly wound. It is tobe noted that resistor strips 30 havea minimumarea of ,con-

tact .with separator rods 26 and a maximum area of vertical passage for contact with the vaporizing substance.

The outer ends-of the conductor ribbons form- .ing the top and bottombanks of loops are con- .nected to vertically spaced terminalposts 32 .ex-

tending through the closure plate 22. Each terminal post 32 has an .integralflange 33 intermediate its ends and spools 34 and 35 ad acent the opposite ends adapted to cooperate with clamping nuts turned ontheextreme endsof theposts which are threaded to receive them. Split insulated bushings 36 surround the postsbetween the flange .33 andthe spools 34 and 35. Insulat- [31, betweenthe blocks 38 and the outer ring 31,

and-between the "flange 33 andtheltwo rings on opposite sides thereof 'toprevent anyileakage of heating vapor. The two terminal posts 32 are in vertical alignment and theends of the conductor ribbon strips connected'thereto areibent and twisted slightly as shown in Figure 3 to make contact therewith. IInFigure 3, the end of the conductor strip forming the bottom bank of1loops is broken off short of its terminal post'32to avoid obscuring the showing of the manner of attachment of the uppermost strip'3ll to ithepost.

A cylindrical terminal box 40 is secured to "the closure 22 by studs 4|. The outer'face of the closure has a circulargroove'dz adaptedto accommodate the inner edge of the box. A cover 43 is removably secured to the outer end of'the box by studs 44. 'A tappedhole 45 is provided at the bottom of theiboxfor "the connection of a conduit 'throughwhich suitable electrical conductors from a direct "current or single phase power source extend to the outer ends of posts 32.

In a preferred'embo'diment ofthis invention,

illustrated in Figures 11 to 16, inclusive, anelectrio immersionheater '50 comprises a horizontal elongated frame having spacedside bars-5 I rigidly attached to a closure plate'or' base 52. which serves the same purpose asbase 22'in1theiembodiment earlier described. Bars5l aresecured together ati'their inner ends by through bolts "53 having spacer sleeves 54 thereon. *A lattice-work insulator comprising a'plurality of insulating spacer I lattices '55 are carried by and between bars '5! transversely thereto and in. spaced relation therealong. Each lattice 55 includes a plurality of Strips 56 are positioned between bars I5l 'in substantially parallel relation thereto and definetaplurality of parallel lanes betweenthe said" bars. Lattices 55 lane formed "by the aligned lattices .55.

'6 also include a plurality, of horizontally positioned supporting rods 51 which are inserted through transverse registering .holes in side bars Stand separator strips 56. 'These transverse registering holes are provided in vertical planes transverse to bars "Slat spaced intervals therealong, said vertical planes coinciding with the longitudinal spacing of lattices 55. The axes of the transverse registering'holes "are located at right angles to separator strips 55 and the holes are sufiicientlylarger than supporting rods 15.! teallow for movement of supporting rods 51in the event of ,any differential expansion or contraction. .For the same .reason, those of the rods .51 which pass through bars.,5l, as shown in Figure 14, terminate somewhat short of the outer surfaces thereof.

Separator strips 56. and supporting ,rods'51 are composed of insulating material such as glass, porcelain or the like, and are assembledininterlocking relation to constitute the series of "lattices 55, each of which defines .a plurality of closed cells in parallel lanes "in axial or'longitudinal alignment with the cells and parallel lanes defined by the immediate lattice or lattices 55 on each side. Separator strips 55 may extend, as shown in Figure 11,;for a length .of more than the distance betweenadjacent flattices '55, or each strip mayextendlmldwayibetween lattices. Vertically, the strips 156 may cover the entire depth of thefheater Silasshown in Figure 13 or separate stripsmay be provided for each bank and be substantially positioned one atop the other, edge to edge. Qutermost strips 56, like outermost rods "26, are slightly shorter than the intermediate strips 156 and uppermost andlowermost supporting rojds j5l rest thereon. "These uppermost and lowermost rods 51, which serve the same purposeas the uppermost and lowermost rods '2'! in the other embodiment described in this invention, are notched at 51"for reception respectively of the bent ends of clamping straps 58. These straps are secured to sidebars 5| bybolts59 as illustrated in Figure 14. There is suflicient clearance between clamping strapsi'58 and'the various adjacent portions of the lattices 55 to permit such expansion asmay take place during operation. a

The preferred embodiment of this invention is particularly applicable in .those situations in which the heat inputs or the .voltages used are so great or in which the nature of the resistance element or vaporizing substance is such that more positive insulation of the lanes in each bank,'is desirable. Such insulation is; provided by separator strips .56 whichhave a sensible thickness across the width of --the heaters. Hence, it is desirable to-keep suchlanes, which :are parts of therespectivelattices 55, defined and the strips 56 separated so vapors and the vaporizing liquid'can properly'circulate in the course of operations. In this preferred embodiment a ribbon or strip resistance conductor 60 is provided which resistor is horizontally corrugated, that is, the sinusoidal bends forming the corrugations'appear on'atra-ce on ahorizontal plane. Such a' horizontally corrugated ribbon resistor-E 60 is wound with thecorrugations remaining therein, in lengthwise loops, back and "forth longitudinally, between side bars 5| witheach portion of each loop in each verticallyspacedjbank, of which there are threepositioned in a continuous lTh banksthemselves are spaced apart andj'insulated "from each other 'by'the horizontal supporting 7 rods 51, in the same way that the banks of the earlier described embodiment are insulated from each other by supporting rods 21. Resistor 60 constitutes the bare resistance heating element of heaters 50 and is composed of a suitable metal alloy as that described in connection with resistor 30. A separate length of resistor 60 is used for each bank and the outer or terminal ends of each thereof on one side, as shown in Figure 13, are extended and bent for respective clamping engagement on terminal posts 62, each of which in character and mounting is substantially the same as the terminal posts 32 described in connection with the other embodiment. Because the preferred embodiment in Figures 11 to 16 is adapted to be energized by a S-phase electrical power source system, a single electrical bus connection BI is used to connect ends not connected to terminals 82 of the resistor 63 in the respective banks. Bus connection 6| comprises a back strip Bid and a clamping strip Blb which is fastened to back strip Gla by machine screws 6lc. These machine screws pass through corresponding holes in the non-terminaled ends of the respective resistors 60 to connect all of them electrically as shown in Figure 13 and thus complete the heating circuit. The mode of assembly of lattices 55 and resistors 80 is substantially the same as that described for lattices and resistors 30.

Further, by the use of resistors 68 with the corrugations, a much greater length ribbon may be wound on a frame of given length, which permits either shorter frames or lower heating rate per ribbon area for a given heat input. Assuming the heating rate need not be lowered but that the frame for a given heat input may be shortened, for many services the heaters need not be curved but can be wholly straight and placed in an oblique arrangement tangential to an inscribed circle of lesser diameter than the inside outer diameter of the jacket and concentric therewith. In some cases the saving in length for a given heating capacity will be so great that the heaters 53 can be mounted in the jacket in horizontal radial fashion. Such a foreshortening of the length of the heaters is made possible by the increase in the effective area of contact obtained between the vaporizing substance and the resistors.

ing rate per ribbon area is high, the use of corrugated ribbons increases substantially the heating surface area of the ribbons which can be wound in a given frame and makes such lower heating rates practicable with the accompanying longer life of the liquid.

Although I have illustrated and described a preferred embodiment and a modification of my invention, it will be recognized that changes in the structural details and arrangement thereof may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In an electric immersion heater, in combination, a supporting member, a lattice-work insulator extending along and supported by said member, said insulator having a plurality of lattices therein at spaced intervals, each lattice being formed of a plurality of parallel insulating separators and a plurality of parallel insulating rods, said separators and said supporting rods being disposed substantially at an angle to each other and adapted to supportably engage each In other instances, using liquids which may decompose if the heat other with space for diiferential thermal movement therebetween and to form a plurality of closed cells in each lattice, said closed cells and their respective openings being in substantial axial registry with such cells and their respective openings in an adjacent lattice, and a re sistor looped back and forth through said cells and openings.

2. In an electric immersion heater, in combination, a supporting member, a lattice-work insulator extending along said member, said insulator having a plurality of lattices therein at spaced intervals along the length thereof, each lattice being formed of a plurality of parallel insulating separators and a plurality of parallel insulating rods,. said separators and said supporting rods being disposed substantially at right angles and adapted to supportably engage ach other with space for differential thermal lIlOlG- ment therebetween, said separators and said supporting rods further forming a plurality of closed cells in each lattice, said closed cells and their respective openings being in substantal axial registry with such cells and their respectiv openings in an adjacent lattice, said supporting rods being supported by said member, and a resistor looped back and forth through said closed cells and openings between said separators.

3. In an electric immersion heater, in combination, a supporting member, a plurality of rectangular insulator lattices supported by said member, said lattices being spaced along said member, each lattice having a plurality of closed cells therein extending laterally across said lattice, said closed cells and their respective openings being in substantial axial registry with such cells and their respective openings of an adjacent lattice, each lattice further having a plurality of parallel insuiating separators placed side by side and a plurality of parallel insulating supporting rods, said separators and said supporting rods being disposed substantially at right angles to each other to form said closed cells and adapted to supportably engage each other with space for differential thermal movement therebetween, and a resistor ribbon looped back and forth on edge through said closed cells and openings between said separators.

4. In an electric immersion heater, in combination, a substantially horizontal elongated supporting member, a plurality of rectangular insulator lattices supported by said member, said lattices being spaced along said member and transverse thereto, each lattice having a plurality of closed cells therein extending laterally across said lattice, said closed cells and their respective openings being in substantial registry with such cells and their respective openings of an adjacent lattice, each lattice further having a plurality of parallel insulating separators and a plurality of parallel insulating supporting rods, said separators and said supporting rods being disposed substantially at right angles to each other to form said closed cells, said supporting rods being disposed in a vertical plane and adapted to support said separators with space for differential thermal movement therebetween, said supporting member and said separators ha-ing a plurality of registering holes in a series of vertical planes spaced along the length of said supporting member through which said supporting rods are respectivey inserted, a resistor ribbon looped back and forth on edge on said supporting rods through said closed cells and openings between said separators, and terminals at the ends of said resistor ribbon through which the energizaacross said lattice forming a plurality'of banks,

said closed cells being in substantial axial registry with such cells of an adjacent lattice, each lattice further having a plurality of parallel insulating separators placed side by side and a plurality of parallel insulating supporting rods, said separators and said supporting rods being disposed substantially at right angles to each other to form said closed cells and adapted to supportably engage each other with space for differential thermal movementthercbetween, and a resistor ribbon in each bank looped back and forth on edge on sa-id'supportin'g rods through said closed cells between said separators;

' 6. 'In an electric immersion heater, in combination, a plurality of spaced elongated side bars, a plurality of rectangular insulator lattices supported by said side bars, said lattices being spaced along the length of said side bars and transverse thereto, each lattice having a plurality of parallel insulating separators placed side by side and aplurality of parallel insulating supporting rods, said separators and said supporting rods being disposed substantially at right angles to each other to form a plurality of closed registering cells through said lattices, said supporting rods extending through registering holes in said side bars and through said separators and adapted to support said separators with space for differential thermal movement therebetween, clamping means positioned adjacent said side bars to hold said supporting rods in assembled position, said supporting rod-s further fitting loosely into said registering holes and between said clamping means, a resistor ribbon looped back and forth on edge on said supporting rods between said separators, and terminal means for energizing said resistor ribbon.

7. In an electric immersion heater, incombination, a supporting member, a plurality of rectan ular insulator lattices sup orted by said member, said lattices being spaced along said member and transverse therettyeach lattice having a plurality of closed cells therein extending laterally and vertically across said lattice forming a plurality of banks, said closed cells being in substantial axial registry with such cells of an adjacent lattice, each lattice further having a plurality of parallel insulating separators placed side by side and a plurality of parallel insulating supporting rods placed in a vertical plane, said separators having a greater dimension in the direction of the length of said supporting member than the dimension transverse thereto, said supporting member and said separators having a series of registering holes in a vertical plane therethroug'h spaced along the length of said supporting member and adapted to have said supporting rods inserted therein, a resistor ribbon looped back and forth on edge on said supporting rods' in each bank through said closed cells between said separators, and terminals for said resistor ribbon through which the energize.- tion thereof is efiected.

8. In an electric immersion heater, in combination, spaced side bars, a plurality of lattices spaced along said barsf-e ach lattice including a plurality of parallel separator rods of inenlisting material disposed side by side and a plurality of supporting rodscf insulating material on which said separator rods are carried, said supporting rods being disposed transversely to said separator rods and engaging said side bars, said supporting rods being further disposed substantially in' a. vertical plane, and a resistor ribbon looped back and forth along and between said side bars with each side of each loop thereof being disposed be--'- tween respective separator rods.

9. in an electric immersion heater, in combination, spaced side bars, a plurality ofp'arallel se a rater rods of insulating material disposed vertically side by side between said bars, each of said separator reds having a plurality of transverse registering holes therethro'ugh, each of said sepia:

r ,rator rods further having a greater dimension along the lengthwise direction of said spaced side bars than the dimension transverse thereto, a

plurality of parallel supporting rods of i-nsul'atf 'in-g material adapted to be inserted through said transverse: registering holes andto engage said side bars to support said separator rods, and a resistor ribbon looped back and forth on edge between said separator rods.

sicn in the direction of elongation of said frame member than in the dimension transverse thereto, a plurality of parallel supporting rods of insulating material adapted to be inserted through said transverse registering holes and to'en'gage' said frame member to support said separator 'rods and complete a plurality of lattices, said lattices defining a plurality of banks of laterally adjacent cells, said lattices being in alignment with adjacent lattices, and 'a resistor ribbon looped back and forth on ed'geth'rou'gh each or said cells in each of said banks ll. In an electric immersion heater, in combination, spaced horizontal elongated Side bars, "8.

plurality of parallel separator rods of insulating material disposed vertically side by side in a plu-j rality of parallel planes spaced along and trans-' versely between said side bars, said separator rods extending vertically beyond said side bars, each of said separator rods having a plurality of transverse registering holes :therethrough at right angles to said separator rods, said side bars having holes therethrough registering with corresponding holes in said separator rods, a plurality of paral'lelsupporting rods of insulating material adapted to be inserted through said transversef registering holes to complete a plurality of aligned lattices defining a plurality of banksoif laterally adjacent closed cell's, said supporting rods engaging said transverse registering holes ex;

tending through said side bars being adapted to' supp'ort'said lattices on said side bars, clamping straps extending verticall adjacent each end of said.- supporting rods in each latticev to hold said supporting barsin position, and a resistor ribbon looper back and forth on edge through each of saidplosed cells in each of saidpb anks, said resister ribbon being supported on said supporting 11 rods and having adjacent portions thereof insulated by said separator rods.

12. In an electric immersion heater, in combination, an elongated supporting frame member, a plurality of lattices supported by and spaced along said frame member transversely thereto, a plurality of parallel separator strips of insulating material adjacent said frame member and extending in the direction of its elongation, a plurality of parallel supporting rods of insulating material adapted to supportably engage said separator strips in a plurality of spaced parallel planes intersecting said strips to form said lattices with a plurality of closed cells and parallel lanes, said lanes extending between said spaced parallel planes, and a resistor threaded in loop fashion through said closed cells and back and forth in said lanes.

13. In an electric immersion heater, in combination, horizontal elongated supporting side bars, a plurality of lattices supported by and spaced along and between said side bars transversely thereto, a plurality of parallel separator strips of insulating material positioned on edge between said side bars and substantially parallel thereto, a plurality of parallel supporting rods of insulating material adapted to supportably engage said-separator strips in a plurality of vertical spaced parallel planes intersecting said-strips to form said lattices with a plurality of closed cells and parallel lanes, said lanes extending between said vertical spaced parallel planes, and a horizontally corrugated ribbon resistor looped back and forth on edge through said lanes with substantially each portion of each loop separated by said separator strips.

14. In an electric immersion heater, in combination, horizontal elongated supporting side bars, a plurality of parallel separator strips of insulating material positioned on edge between said side bars and substantially parallel thereto,

a plurality of transverse registering holes through i said side bars and said separator strips, said transverse registering holes being in a plurality of spaced vertical parallel planes between and transverse to said side bars, a pluralityof parallel supporting rods of insulating material adapted to be inserted through said transverse registering holes to complete a plurality of insulating lattices between said side bars having a plurality of closed cells and parallel lanes, said lanes extending on each side of said closed cells substantially between said vertical spaced parallel planes containing said transverse registering holes, and a horizontally corrugated ribbon resistor looped back and forth on edge through said lanes.

15. In an electric immersion heater, in combination, horizontal elongated supporting side bars, a plurality of parallel spacer strips of insulating material positioned on edge between said side bars and substantially parallel thereto. a plurality of transverse. registering holes through said side bars and said separator strips substantially at right angles to said separator strips, said transverse registering holes being in a plurality of vertical planes between and transverse to said side bars and spaced therealong, a plurality of adapted to be inserted through said transverse registering holes to support said separator strips and to complete a plurality of insulating lattices between said side bars, said lattices respectively having a plurality of closed cells and parallel lanes in a plurality of banks, said lanes extending on each side of said closed cells substantially between said spaced vertical parallel planes, a clamping strap adjacent said side bars and the ends of said supporting rods in each said vertical spaced parallel plane to hold said supporting rods in supporting position, and a horizontally corrugated ribbon resistor looped back and forth on edge through said closed cells and said lanes and occupying substantially the entire horizontal dis tance between said strips.

16. In an electric immersion heater, in combination, an elongated frame including a pair of spaced lateral beams each having an upper series and a lower series of holes spaced therealong, the said upper and lower series of holes each lying in a substantially horizontal plane and the holes in opposite lateral beams being in alignment, a plurality of insulating supporting rods extending across said frame from beam to beam each rod reposing at its ends in said holes, generally vertically disposed separator members of insulating material spaced along said rods, each of said separator members extending above and-below the horizontal planes of said holes in said beams and having aligned holes therein through which said rods pass and support said separator members, the said separator members having other aligned holes adjacent their upper and lower extremities, closure rods extending across said heater through said other holes in said separatormembers, the interlocking separator members, supporting rods and closure rods comprising lattices with aligned cells in a plurality of generally horizontal banks spaced longitudinally along said frame, a resistor ribbon looped back and forth through the cells of each bank, and removable means on the sides of the frame closing said holes in said beams and in said separator members adjacent the ends of said supporting rods and said closure rods, whereby when said removable means are removed the cells of the outer banks may be "opened by withdrawing said closure rods for insertion or removal of a resistor ribbon winding, and by removal of the set of supporting rods in either said upper or lower series of holes a resistor ribbon winding may be transferred relative an inner bank without disturbing the balance of said frame and lattices.

HERBERT L. BARNEBEY.

Y. file of this patent:

UNITED STATES PATENTS Number Name Date 1,719,722 Peterson July 2, 1929 1,810,185 Powell June 16, 1931 3 6 Cushman Dec. 1, 1931 1,939,125 Lubbock et a1 Dec. 12, 1933 3357-170 Fahrenwald Jan. 9, 1945 

